Add contacts, reply/forward, pagination, HTML toggle, Docker Compose for VPS

Co-authored-by: Junie <junie@jetbrains.com>

backend/Dockerfile

@@ -1,5 +1,16 @@
-FROM eclipse-temurin:21-jdk-alpine
+# Stage 1: Build
+FROM eclipse-temurin:21-jdk-alpine AS build
 WORKDIR /app
-COPY build/libs/*.jar app.jar
-EXPOSE 8080
+COPY build.gradle settings.gradle gradlew ./
+COPY gradle gradle
+COPY src src
+RUN chmod +x gradlew
+RUN ./gradlew bootJar --no-daemon
+
+# Stage 2: Run
+FROM eclipse-temurin:21-jre-alpine
+WORKDIR /app
+COPY --from=build /app/build/libs/*.jar app.jar
+RUN mkdir -p /app/attachments /app/dkim-keys
+EXPOSE 8080 3025
 ENTRYPOINT ["java", "-jar", "app.jar"]